The present invention is related to a control valve assembly structure for spray guns, comprising a pistol body made up of water inlet and outlet conduits in fluid communication with a valve chamber having a control valve assembly mounted therein wherein a pressing guide surface of a plunger is closely abutted tight against a water-sealing portion of a flexible valve, and flexibly pushed and supported by a spring element so that force can be evenly applied onto the water-sealing portion thereof, facilitating an accurate and smooth operation thereof. Besides, the flexible valve is simplified in structure to provide an easier processing and save the cost in the making of mould for the economical efficiency thereof.
Please refer to FIGS. 1, 2. A conventional spray gun structure as disclosed in the U.S. Pat. No. 6,796,515B2 includes a spray gun 10 wherein a pistol body 11 is equipped with a valve chamber 111 and a valve shaft 12 mounted to a flexible diaphragm 13 at the valve chamber 111 therein. The control diaphragm 13 is clamped and located by an end cover 14 and a valve seat 15 to form a water seal-off state. When the valve shaft 12 is pushed, the flexible diaphragm 13 affected by the fluid pressure generated inside the pistol body 11 will be expanded to detach from the valve seat 15 thereof, permitting the fluid flow accommodated in an inlet conduit 16 to come into the valve seat 15 before sprayed outwards via an outlet conduit 17. However, the flexible diaphragm 13 simply makes use of the tension to control the shutoff or discharge of fluid flow, which is complicatedly structured and may increase the cost in the making of mold thereof. Besides, the flexible diaphragm 13 is fixedly located by the end cover 14 and the valve seat 15 and can only depend on the tension produced by the interior pressure of the pistol body 11 to control the operation thereof, which can easily cause flexible fatigue of the diaphragm 13 under the repeated expansion and contraction thereof and lead to awkward and jamming operation thereof.